1. Technical Field of the Invention
The present invention relates, generally, to a sewing machine with an adjustable head module.
More particularly, the present invention relates to a sewing machine with an adjustable head module, wherein the head module is pivotably mounted on a support arm and swings about a horizontal pivot bearing in a first sewing direction ("A"), and axially displaceable in a sewing second direction ("B.")
2. Description of the Prior Art
Sewing machines having a modular structure are currently known to the prior art. Such machines usually consist of various structural components, which are manufactured in different locations and subsequently assembled. The assembly of the various structural components generally requires costly adjustment work and, further, very precise execution of various points of connection between the individual structural components. Moreover, adjustment between a subassembly supporting the sewing machine needle and a subassembly receiving the looper is very difficult. Any adjustment of these two subassemblies, short of what would be consider optimal, may lead to incorrect stitching and needle fractures and, of course, less than perfect formation of the stitches.
A sewing machine with a modular structure is known to the art, for example, from Killinger, U.S. Pat. No. 4,421,042, issued Dec. 20, 1983. The sewing machine described in U.S. Pat. No. 4,421,042 includes a housing with a plate supporting a workpiece, and a supporting arm arranged above the plate supporting the workpiece. The plate supporting the workpiece receives the looper and the mechanism advancing the workpiece. The supporting arm accommodates the needle bar, the presser foot drive and a component for tensioning the thread. The driving motor, the driving shaft and the driving elements driving the needle bar, the presser foot bar, as well as the looper and the device transporting the material being sewn, are installed in the housing. The three subassemblies, discussed above, are connected by means of screws and, inasmuch as no adjusting means are present, the accuracy or precision in the manufacture of the elements, joining the three subassemblies, is expected to meet extremely high requirements.
A similar device is known from Sanvito et al., U.S. Pat. No. 4,590,875, issued May 27, 1986, in which a subassembly, with the needle bar drive and the fabric presser drive, and, below, a subassembly with the looper and the means for driving the material to be sewn, can be screwed to a housing on the supporting arm as well; said housing receiving the drives. The precision of the individual subassemblies has to satisfy extremely high requirements with this prior art apparatus, as well, because adjustment of the individual subassemblies is either not possible or possible, but to only a limited extent and, then, only with the expenditure of a substantial amount of time and effort.